In recent years, attempts have been made to produce various three-dimensional structures using prototyping technique utilizing computers. For example, patent document 1 described a configuration in which metal material is molten and Jetted from a nozzle, the nozzle or support means of a three-dimensional structure is moved in accordance with structure data of the three-dimensional structure to be produced, and a desired three-dimensional structure is produced.
(Patent Document 1)
Japanese Patent Application Laid-open No.H10-193079(page 2, column 1, patent claim, page 3, column 4 (0007) to page 4 column 5 (0009), and FIGS. 1 to 3)
In a method using metal jet such as a prototyping technique, when molten metal is jetted into air from a nozzle, since the temperature of the molten metal is high, the molten metal reacts with oxygen in the air in the vicinity of an outlet of the nozzle and is oxidized, and they become a metal oxide such as ceramic. Since the metal oxide is accumulated in the vicinity of the outlet of the nozzle, the nozzle is clogged and the molten metal can not be jetted in many cases. If molten metal is oxidized immediately after It is discharged, molten metal droplets are not formed into spherical shape but are formed into shape having a tail. Therefore, the metal droplets are formed irregularly or a desired product can not be obtained in some cases.
Hence, it is an object of the present invention to prevent clogging of a nozzle hole which jets molten metal.
It is another object of the invention to form molten metal droplet into a spherical shape.